190 OLAF GALLOE 
Stereocaulon denudatum, podetia-wandering fruticose lichen. 
Sphærophorus fragilis, — 
— coralloides = 
Cetraria aculeata, — 
Cladonia pyxidata, hypothallus-wandering fruticose lichen. 
== gracilis, = 
— cornucopioides, = 
Cetraria islandica, erect foliaceous lichen. 
Peltigera canina, procumbent foliaceous lichen. 
— rufesceus, — 
— aphtosa, — 
Solorina crocea, — 
Pertusaria corallina, crustaceous lichen. 
Sterile crustaceous lichens. 
Altogether about 18 species. Quantitively, as far as it appears, 
the fruticose lichens are decidedly dominant in some places. Thus, 
Jönsson has seen them in such abundance amongst Grimmia, 
that he calls them “indicative of Lichen-heaths.” But this appears 
to be only true of patches here and there. I myself have not met 
with this phenomenon. In Denmark we have nothing that can be 
compared with the Icelandic Grimmia-carpets, as regards superficial 
extension. Where we, here and there, find Grimmia-bogs scattered 
in our heaths, they are generally small, and appear to be wetter 
at the bottom, than are those in Iceland, and are consequently 
practically devoid of lichens. The difference no doubt chiefly de- 
pends on the fact, that in Denmark the Grimmia-bogs usually occur 
in damp hollows, where stagnant ground-water furnishes them with 
the necessary moisture, whilst the Grimmia-carpets in Iceland are, 
in a higher degree, directly furnished with this by rain. The 
Grimmia-carpets in Denmark have, as a rule, undoubtedly a quicker 
vertical growth, and deeper peat-substratum, which explains the 
characteristic paucity of lichens in our Grimmia-carpets, and the 
lichen-wealth in those of Iceland. It is consequently, in the first 
instance the competition which is stronger and more inimical to 
lichens in Denmark than in Iceland. 
Besides this, it is strange that the Iceland Grimmia-carpets can 
contain quantitively, such an abundance of crustaceous lichens, 
whilst ours are quite devoid of them. 
A Table will render the difference plain: — 
